1. Field of the Invention
The present invention relates to the improvement of a heddle frame.
2. Description of the Prior Art
A heddle frame as generally used in a weaving machine is composed of a pair of lateral beams 1' and a pair of side stays 2' as shown in FIG. 1A. A projection 3' formed at an inner end of a side stay 2 is connected to an inner hollow end portion 4' of said lateral beam 1', whereby the end portion of the lateral beam 1' and the end portion of the side stay 2' are fixed tightly.
However, in an ordinary heddle frame, the outer periphery of the side stary 2' which is fitted to freely slide into a guide groove formed in a guide apparatus, is vertically moved upwards or downwards by actuating the side stays by the aid of a dobby and shedding motion which is performed vertically, during which motion the pair of lateral beams 1', 1', remain in a free state. Therefore, the inertia force caused by the vertical shedding motion is applied to the upper lateral beam 1' and the lower lateral beam 1', whereby the pair of the lateral beams 1' have the tendency to bend into a convex state toward upper direction during the upward stroke of the vertical motion thereof as shown in FIG. 1A, and the pair of the lateral beams 1' have the other tendency to bend in a convex state toward lower direction during the downward stroke of the vertical motion, as shown in FIG. 1B. These tendencies are especially acute in the case of a high speed weaving machine operated with a rotation of 300 rpm to 600 rpm.
Further, the strength of the side stay 2' is too strong for it to be bent as shown in FIG. 1A or in FIG. 1B; generally the strength of the side stay 2' being stronger than that of the lateral beam 1'. As a result, a large bending moment is applied to the connection portion of the side stay 2' and the lateral beam 1'. Moreover, this large bending moment is applied alternately and there arises the possibility that the connection portion of the side stay 2' and the lateral beam 1' can be damaged or cut off.
Further, in the case of the connection by a bolt and a nut at the connection portion of the side stay 2' and the lateral beam 1', the tightness by the bolt and the nut may be loosened by the alternate large bending moment applied to the connection portion of the side stay 2' and the lateral beam 1'. This loosening induces noise pollution during the shedding motion of the ordinary heddle frame.
Recently, the weaving speed of newer weaving machines has increased. This high speed motion requires that every part possess more strength, and that every part become relatively complex and heavy. The inertia due to the weight of the heddle frame thus becomes larger. Therefore, every part is bent more by the larger inertia force, and the life of the heddle frame becomes shorter, and there arises a defect that a tremendous noise is produced by the friction arising in the transmission system.
To delete the defects mentioned above, there are many cases in which a lightweight aluminum hollow body is used as a lateral beam. However, the bending tendency of the lateral beam of aluminum cannot be completely eliminated and there remains the defect that the connection portion of the side stay and the lateral beam has the strong tendency to deteriorate.